Honestly my main reason that I am happy with the Wii U as a "system" is that even my 5-year olds can use their Wii Motion controllers and because they have excellent games like Super Mario 3D World that are great for me (at 30+ age) and my kids at just 5 years. Even better if we all play together with me on the gigantic gamepad as the controller and the kids using their favored Wii Motion controllers held sideways.
They have shown interest in PS3 or X360 games, but their hands can't work those much larger controllers. They also can't use the Wii U Pro or Gamepad controller. They also can't use the PS-Move.
For what its worth, the Kinect doesn't pick up their motions properly either cause they are too dainty (small). So currently they can only use 3DS, Vita, or Wii-motes.
